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排序方式: 共有312条查询结果,搜索用时 296 毫秒
31.
E Sindern C Oreja-Guevara M Raulf-Heimsoth X Baur JP Malin 《Canadian Metallurgical Quarterly》1997,151(1):29-34
We investigated sequential changes in bile flow, serum and biliary biochemical parameters in phalloidin-induced cholestasis in rats. Intrahepatic cholestasis was induced by administration with phalloidin (500 microg/kg) for 7 days, and then the animals were allowed to survive for 1, 2, 4, 7, 14 and 28 days after the last treatment. In phalloidin-treated rats, bile flow significantly decreased up to 4 days of recovery, compared with the control animals. In contrast, serum ALP activity, LAP activity, cholesterol concentration and phospholipid concentration exhibited a marked elevation throughout the recovery periods. For biliary parameters, bilirubin excretion rate was unchanged but, cholesterol excretion rate showed a marked decrease throughout the recovery periods. These results demonstrate that some parameters, particularly important indexes of cholestasis (serum ALP, cholesterol, bile flow and so on), continued significant changes at least 4 days after the last administration of phalloidin. These results demonstrate that successive treatment with phalloidin can cause damage in most of serum and biliary parameters at a chronic stage of cholestasis. Thus, our findings may provide useful information for diagnosis of drug-induced cholestasis and help to further elucidate the biochemical mechanisms of drug-induced cholestasis in humans. 相似文献
32.
33.
Malin Falkenmark 《国际水资源开发杂志》2004,20(3):275-281
A recently launched international initiative on “Hydrology for the Environment, Life and Policy” (HELP) aims at a science‐based approach to integrated catchment management, and in particular to facilitating the dialogue needed between scientists, stakeholders and policy makers. The ultimate challenge of a sustainability‐oriented environmental management is to find the proper balance between humans and the impacts that their activities cause to ecosystems. This makes the catchment a useful landscape unit for an integrated approach where a balancing between humans and nature can be carried out. The catchment can be seen as containing two mosaics, one of human water‐related activities and the other of water‐dependent ecosystems, terrestrial as well as aquatic. These two mosaics are internally linked by water flows but partly incompatible. Therefore, a management task is to orchestrate the catchment for compatibility, which will demand intentional trade‐offs. Past water management policy has often been based on outdated knowledge and technology, for instance by a ‘paradigm lock’ between scientists and stakeholders, isolating them from each other: scientists by the lack of proven utility of their findings, and stakeholders by legal and professional precedence and disaggregated institutions. The HELP initiative encourages the water policy, water resources management and scientific communities to work together within a field‐oriented context so that science may be closely integrated with policy and management needs. 相似文献
34.
The requirements of materials for use in the core section of unenriched uranium type nuclear reactors are, to a large extent, fulfilled by zirconium alloys. However, the operating temperature of such reactors is circumscribed by the inability of the presently available alloys to maintain their properties at temperatures exceeding 350–400° C. This paper is concerned with the selection of alloying elements for the improvement of the high temperature strength of zirconium alloys and reports the results obtained from a study of the phase transformations in dilute Zr-Cr alloys. 相似文献
35.
This article deals with the effect of orientation on the electrical properties (tangent of the angle of dielectric losses tan δ, electric strength E, and lifetime τ) of polymer films. It is shown that the orientational stretching of PVC and PC films leads to the change of the temperature position of dipole segmental losses and reduces the value of tan δ in the maximum of this region. Under the orientation the electric strength of PE and PVC films increases considerably, and the lifetime τ increases under the high strengths of the field, and reduces under the low ones. The mechanical loads causing no orientation only reduce the lifetime of the polymer films. 相似文献
36.
We determined serum and cerebrospinal fluid (CSF) levels of the soluble 60-kDa tumour necrosis factor (TNF) receptor (sTNF-R p60) in 50 patients with relapsing-remitting multiple sclerosis (MS) and in 18 patients with Guillain-Barré syndrome (GBS). Neither in serum nor in CSF samples was there a statistically significant difference between mean receptor concentrations of patients with MS (serum: 1064, SD 262 pg/ml; CSF: 555, SD 130 pg/ml), with other noninflammatory neurological diseases (serum: 1008, SD 248 pg/ml; CSF: 530, SD 112 pg/ml) and with healthy control subjects (serum: 918, SD 180 pg/ml). In order to determine disease activity, magnetic resonance imaging (MRI) of the brain was performed in all MS patients. The mean sTNF-R p60 levels of patients who showed gadolinium DTPA enhancement on MRI were not different from those without enhancement (1034, SD 274 pg/ml vs 1099, SD 248 pg/ml in serum samples and 546, SD 109 pg/ml vs 565, SD 152 pg/ml in CSF samples). In GBS, the sTNF-R p60 levels of serum and CSF samples were significantly higher than in MS and all control groups except for the group with viral meningitis (VM) (GBS: 1544, SD 834 pg/ml in serum, 882, SD 147 pg/ml in CSF; VM: 1518, SD 375 pg/ml in serum, 1131, SD 611 pg/ml in CSF; P < 0.001 for serum samples and P < 0.005 for CSF samples). Serial serum sTNF-R p60 measurements in 13 patients with GBS showed an increase in receptor levels parallel with the recovery from the disease (1276, SD 374 pg/ml at the time of disease onset, 1554, SD 482 pg/ml 14-24 days later and 1787, SD 525 pg/ml after 28-32 days). From our results and the conflicting data of previous studies, we could not agree with the suggestion that the assessment of sTNF-R p60 in MS patients is a useful marker for disease activity. In GBS, subsequently increasing sTNF-R p60 levels are associated with recovery from the disease. It remains to be shown whether they might represent a relevant pathogenetic factor during this stage of GBS. 相似文献
37.
Waldenstr?m M?ns; Josephson Malin; Persson Cathrine; Theorell T?res 《Canadian Metallurgical Quarterly》1998,3(3):209
This study presented and evaluated an interview method for the analysis of tasks included in a work situation. What mental demands and possibilities do the work tasks give rise to? When was the work more or less automatic? When was use of active knowledge required? When were problem solving and planning needed? The study included an assessment of the interobserver reliability of the interviews with employees from 5 different careers: bus drivers (n?=?10), home service workers (n?=?32), carpenters (n?=?11), farmers (n?=?14), and teachers (n?=?26). The extent to which this method can be reproduced in studies of different occupations is discussed. The interobserver reliability was good (.75–.82). There is support for the stability and usefulness of the interview for most types of work concerning the 3 categories of mental demands: routine, active knowledge, and problem solving/creativity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
38.
200 women threatened with abortion during the first 16 weeks of pregnancy were examined with diagnostic ultrasound to determine whether there were signs of intrauterine life. Of the 90 who showed positive signs, 8 aborted spontaneously later, the other 82 continued their pregnancy. The ultrasound investigation revealed no signs of intrauterine life in 110 patients. Of these, spontaneous abortion or later evacuation because of missed abortion 101 (histopathological examination showed degenerated villi in 98), not pregnant 4, mola hydatidosa 3, extrauterine pregnancies 2. An ultrasound examination was performed to ascertain whether 136 women with suspected ectopic pregnancy had intrauterine pregnancies. 61 of them had an intrauterine gestational sac, confirmed at clinical follow-up. One of the 61 was operated on with laparoscopy because of pain; no abnormalities were found. In 36 of the other 75, laparoscopy was performed. Ectopic pregnancy 21, ovarian or parovarian cyst 11, adhesions 2, salpingitis 1, and normal 1. Diagnostic ultrasound is excellent for accurate prognosis in threatened abortion. Unnecessary operations avoided; hospitalization in suspected ectopic pregnancies reduced. 相似文献
39.
Malin Berggrund Hanna Härelind Ingelsten Magnus Skoglundh Anders E. C. Palmqvist 《Catalysis Letters》2009,130(1-2):79-85
The influence of syntheses parameters of zeolite ZSM-5 on the lean NO x reduction activity and hydrothermal stability of Cu-ZSM-5 has been investigated. The hydrothermal stability of Cu-ZSM-5 was found to depend on the aluminium source used and on the presence of Ca(OH)2 in the synthesis mixture for ZSM-5. 相似文献
40.
近年来,环境治理和清洁能源生产已被视为世界的当务之急。利用可再生太阳能进行光催化反应是解决上述问题的一种有效途径。光催化体系较为复杂,光催化剂和助催化剂是影响光催化效率的两个关键因素。具有独特电子结构的过渡金属磷化物(TMPs)价格低廉、储量丰富,已成为光催化材料研究领域的新热点。本文从光催化效率提高的基本原理(光吸收增强、光生电子和空穴分离效率以及载流子利用率提高等)出发,综述了近十年来TMPs作为助催化剂和光催化剂的最新研究进展。最后,总结了TMPs在快速发展过程中依然存在全解水困难以及结构与光催化活性对应关系不明确等挑战,通过双功能TMPs的设计和理论计算的配合,新型高效光催化材料TMPs会对光催化效率的提高发挥重要作用。 相似文献